@raphael_tillman 
To put a p5.js canvas inside an HTML <div> element, you can create the canvas in your JavaScript code and then append it to the desired <div> element. Here's an example:
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<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>p5.js Canvas in a Div</title>
    <script src="https://cdnjs.cloudflare.com/ajax/libs/p5.js/1.4.0/p5.js"></script>
</head>
<body>
    <div id="canvasContainer"></div>
    
    <script src="sketch.js"></script>
</body>
</html>
 | 
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function setup() {
    let canvas = createCanvas(400, 400);
    canvas.parent('canvasContainer'); // Append the canvas to the div with id 'canvasContainer'
}
function draw() {
    background(220);
    ellipse(width/2, height/2, 50, 50);
}
 | 
In the above code, we create a canvas using createCanvas() and then use the parent() function to append the canvas to the <div> element with the id 'canvasContainer'.
This is how you can put a p5.js canvas inside an HTML <div> element.